Input
Output
<!DOCTYPE html> <html> <head> <style> body, html { height: 100%; margin: 0; } .center-box { width: 200px; height: 200px; background-color: lightblue; position: absolute; top: 50%; left: 50%; transform: translate(-50%, -50%); display: flex; justify-content: center; align-items: center; } </style> </head> <body> <div class="center-box">Center</div> </body> </html>